The world No. 1 learned of his grandfather Vladimir's passing just hours before the match, but the Serb battled on to progress to the quarter-finals.

It is understood Djokovic was particularly close to his grandfather, who sheltered he and his family during the NATO bombing of Belgrade in 1999. After the match, Djokovic wiped tears from his eyes before pointing to the sky, dedicating the victory to Vladimir.

Djokovic did not front the media immediately after the win, leaving ATP officials to release a statement which read: "Novak Djokovic would like to ask for your understanding.

"As you know, he lost his grandfather today just before the match, and it was very hard for him to play. After he won, he just felt totally exhausted physically, mentally and emotionally."

It is not yet known whether Djokovic will continue to play in the tournament or return to his homeland to grieve.